I constantly hear from dads who remember from high school physics classes that mass doesn’t affect the rate at which something falls. If dropped in a vacuum, a bowling ball and a feather fall at exactly the same speed, so the same should be true of a Pinewood Derby car as well, right? If this logic holds up, a three ounce car should be just as fast as a five ounce car.
The problem with this logic is twofold. We’re not just testing the rate at which something falls; on most tracks, half the track is sloped and half is flat. And we aren’t running in a vacuum; there’s lots of friction involved.